1. Technical Field
This invention relates to a method for producing a recording head of the liquid ejecting type which exhibits low stress and high resistance against chemicals and which includes a plural number of flow ducts formed to high accuracy by patterned shaping by e.g. radiation of ultraviolet light.
2. Description of Related Art
Among the liquid ejecting type recording heads, there is an ink jet recording head applied to the ink jet recording system, ejecting e.g. the ink as liquid (liquid jet recording system). This ink jet recording head includes several constituent units, namely a plural number of ejecting orifices (orifices) ejecting the ink in a finely divided form, a plural number of flow ducts communicating with these ejecting orifices, and by a plural number of ink ejecting pressure generating devices, provided in certain portions of the flow ducts. For generating a high quality image with such ink jet recording head, it is preferred that small ink droplets, discharged from the ejecting orifices, are discharged with the same volume and at the same ejecting speed at all times from the respective ejecting orifices.
Among the ink jet recording heads, realizing these ejecting conditions, there are those stated for example in the following Patent Publication 1 (JP Laid-Open Patent Publication S56-123869), Patent Publication 2 (JP Laid-Open Patent Publication S57-208255), and Patent Publication 3 (JP Laid-Open Patent Publication S57-208256). In the ink jet recording head, disclosed in the Patent Publications 1 to 3, a plural number of nozzles, each including an ink flow duct and an orifice part, are patterned with e.g. a photosensitive resin material or a photoresist, on a substrate carrying a plural number of ink ejecting pressure generating devices. On a component part, carrying the ink flow ducts and the orifice parts, there is bonded a lid formed by, for example, a glass plate. Examples of the photosensitive resin material or the photoresist include diazo resin, p-diazoquinone, photo-polymerized photopolymers, containing vinyl monomers and a polymerization initiator, dimerized photopolymers, employing e.g. polyvinyl cinnamate and a sensitizer, a mixture of orthoquinone diazide and a phenol novolak resin, and a mixture of polyvinyl alcohol and diazo resin. Other examples include polyether photopolymers, obtained on copolymerization of 4-glycidyl ethylene oxide with benzophenone or glycidyl calcone, an N-N-dimethyl methacryl amide-acrylamide benzophenone copolymer, unsaturated polyester based photosensitive resin, unsaturated urethane-based photosensitive resin, and a photosensitive composition obtained on mixing a difunctional acrylic monomer with a photopolymerization initiator and a polymer. Further examples include a dichromate photoresist, a non-chromium-based water-soluble photoresist and a polyvinyl cinnamate based photoresist.
Other ink jet recording heads, satisfying the aforementioned conditions for ejecting, may be exemplified by an ink jet recording head, obtained by a method for preparation as disclosed in Patent Publication 4 (JP Laid-Open Patent Publication S61-154947), indicated below. In the method for the preparation of the ink jet recording head, disclosed in the Patent Publication 4, a plural number of ink flow duct patterns are formed on the site of the substrate, which become to be ink flow ducts, with a dissolvable resin, and the so formed ink flow duct patterns are coated with an epoxy resin. The substrate is then severed, and the dissolvable resin, which forms the ink flow duct patterns, is dissolved and removed to yield an ink jet recording head.
There is also such an ink jet recording head in which, in contrast to those shown in the Patent Publications 1 to 4, a plural number of electrical thermal transducers, as the ink ejecting pressure generating devices, are mounted facing the ejecting orifices, with the direction of growth of the air bubbles, formed on the electrical thermal transducers, being substantially the same as the ink ejecting direction. Examples of this type of the ink jet recording head are disclosed in the Patent Publication 5 (JP Laid-Open Patent Publication S58-8658) and Patent Publication 6 (JP Laid-Open Patent Publication S62-264957), indicated below. In the ink jet recording head, disclosed in Patent publication 5, a dry film, which later becomes an orifice plate, is bonded on a substrate, provided with the electrical thermal transducers, with another patterned dry film. A plural number of ejecting orifices are formed by a photolithographic technique on the sites facing the electrical thermal transducers of the dry film and which later become an orifice plate. In the ink jet recording head, disclosed in Patent Publication 6, the substrate, carrying the ink ejecting pressure generating devices, and an orifice plate, prepared by electrocasting, are bonded together via a patterned dry film.
Moreover, in the ink jet recording heads, it is necessary not only to eject the ink with the same volume and at the same ejecting speed via ink ejecting orifice but also to eject fine ink droplets at accurately set positions. In order for the ink jet recording head to eject the ink at these accurately set locations, the distance between the electrical thermal transducer and the ejecting orifice, referred to below as ‘OH’ distance, is desirably as short as possible.
An illustrative method for producing an ink jet recording head, the OH distance of which has been set to high accuracy, is disclosed in Patent Publication 7 (JP Laid-Open Patent Publication H6-286149). In this Patent Publication 7, there is disclosed a method for preparation of an ink jet recording head including an ink flow duct pattern forming step, a coating resin layer forming step and a dissolvable resin layer dissolving step. In the ink flow duct pattern forming step, an ink flow duct pattern, which later becomes an ink flow duct, is formed by a dissolvable resin on a substrate already carrying ink ejecting pressure generating devices. In the coating resin layer forming step, the coating resin, containing an epoxy resin, solid at ambient temperature, is dissolved in a solvent and applied by solvent coating on a dissolvable resin layer, forming an ink flow duct pattern, to form a coating resin layer, which later becomes a wall section of an ink flow duct, on the dissolvable resin layer. In the resin layer dissolving step, the dissolvable coating layer, forming the ink flow duct pattern, is dissolved. In the method for producing an ink jet recording head, described in Patent Publication 7, a cationic polymer of an alicyclic epoxy resin is used as the coating resin from the viewpoint of forming a high aspect ratio pattern and of assuring high resistance against the ink.